1. Field of the Invention
This invention relates to an IC memory card including electronic elements.
2. Description of the Related Art
FIG. 10 is a perspective view showing a conventional IC memory card. FIG. 11 is cross-sectional view showing the conventional IC memory card shown in FIG. 10 and taken along line 11--11 of FIG. 10. As shown in FIG. 11, the IC memory card comprises a U-shaped frame 3 made of resin or the like, a connector 6 mounted on the open end of the U-shape frame 3 to form a rectangular frame, and two substantially rectangular panels 4 bonded to the upper and lower sides of the frame 3 and the connector 6. Each of the panels 4 is bonded at its outer edge to the inside surface to the frame 3 by an adhesive agent 5. The IC memory card 7 includes a circuit board 2 supported by the frame 3 and the connector 6 and having electronic elements 1 disposed thereon. The connector 6 is, as shown in FIG. 10, disposed on either of the shorter sides of the IC memory card 7. The connector 6 has tens of socket contacts 8 per line, the socket contacts 8 being disposed in two lines. Each of the socket contacts 8 includes a hole perpendicular to an external-unit connection surface 20 of the connector 6. Each socket contact 8 includes a terminal 9 electrically connected to an electronic element mounted on the IC memory card 7.
FIG. 12 is a schematic and enlarged cross-sectional view of the connector 6 shown in FIG. 11. The connector 6 is made of resin or the like by a molding process. The connector 6 comprises a rectangular parallelepiped connector body 6b and flange portions 6a, the connector body 6b including the socket contacts 8 (see FIG. 10). The flange portions 6a are each adjacent to the connection portion of the connector body 6b for establishing a connection with an external unit, the flange portions 6a forming the outer surface of the IC memory card 7 in the connector portion and lying in the same plane as the main surfaces of the panels 4. The connector 6 has a symmetrical cross-section parallel to the main surfaces of the panels 4.
IC memory cards have a standard size (width L:54.0 mm.times.length D:85.6 mm and thickness T:3.3 mm) according to, for example, the guideline issued by the Japan Electronic Industry Association.
A connector (omitted from illustration) of an external unit, into which the IC memory card 7 is inserted, is composed of a connector surface having a substantially rectangular shape and a frame-shape connector guide located around the outer end of the connector surface. The connector surface has contact pins (omitted from illustration) which are terminals electrically connected to the internal system of the external unit, the contact pins having a configuration complementary to the socket contacts 8 disposed in the connector 6 of the IC memory card 7. The contact pins project and correspond to the socket contacts 8.
With the conventional IC memory card, the connector 6 disposed on the shorter side of the IC memory card 7 is inserted into the connector of an external unit (omitted from illustration) through an insertion port in the external unit (omitted from illustration) for receiving the IC memory card 7. The socket contacts 8 disposed in the connector 6 of the IC memory card 7 and the contact pins (omitted from illustration) disposed in the connector of the external unit correspond to one another and thus the electrical connection is established. As a result, the IC memory card 7 and the external unit are electrically connected to each other.
The conventional IC memory card usually has the connector 6 on either of the shorter sides of the IC memory card 7 as shown in FIG. 10. However, a suggestion has been made in, for example, Japanese Patent Application No. 6-46020, which is not a known technology, for an arrangement with the connector 6 on either of the longer sides of the IC memory card in order to increase the number of the poles of the connector yet maintain the standard size of the card. The IC memory card of the foregoing type comprises a connector that is longer than the connector 6 disposed on the shorter side of the IC memory card.
Ideally, the connector 6 has a cross-sectional shape that is axially symmetric about a plane parallel to the main surfaces of the panels 4. However, it is difficult to make the vertical flanges 6a the same size (height A and width B). Unavoidable dimensional errors and errors occurring during manufacturing cause a slight difference. If there is a slight difference between the sizes of the vertical flange portions, the connector 6 is warped so that the vertical flange portion having a larger cross-sectional area forms a concavity because the contraction is larger for the flange portion which has a larger cross-sectional area (see FIG. 13).
The warping of the connector 6 is substantially proportional to the length of the connector 6 so that lengthening of the connector 6 causes the warping to increase. If the connector 6 is warped excessively, the IC memory card 7 cannot easily be assembled. If the IC memory card 7 is forcibly assembled, distortion of the overall body of the IC memory card 7 takes place, causing problems when connection with an external unit is established. Therefore, warping is a critical problem with an IC memory card of the type comprising a connector 6 disposed on the longer side. The problem of excessive warping also arises with the connector 6 when the flange portion has a large volume because the amount of the contraction is increased.
In the conventional IC memory card arranged as shown in FIGS. 10 and 11, the panels 4 are bonded to the frame 3 by the adhesive agent 5 only at the periphery of the panels. The panels 4 are not supported by other portions. Therefore, if a vertical force acts on the main surface of the panel 4, the panel 4 will easily be deformed, particularly at the central portion. As a result, the panel 4 is undesirably pressed against the electronic element 1 mounted on the circuit substrate 2, and, therefore, the electronic elements 1 may be broken.
Heat generated due to electrical power dissipation of the electronic elements 1 when the IC memory card 7 is activated is discharged through two main routes. One of the two routes is from the surfaces of the electronic elements 1 to the ambient through air in the IC memory card 7 and the surfaces of the panels 4. In a residual route, heat is transmitted from the electronic elements 1 to the circuit substrate 2 through leads of the electronic elements 1 and then it is discharged from the surface of the circuit substrate 2 to the ambient through air in the IC memory card 7 and the surface of the panel 4. When the electronic elements 1 are operated actively, the electronic elements 1 generate a large amount of heat. If the temperature in the IC memory card 7 rises, the IC memory card 7 may operate erroneously or the bonded portion between the panels 4 and the frame 3 may become separated.
In a conventional system for establishing a connection between the IC memory card 7 and the external unit, the socket contacts 8 of the IC memory card 7 and the connect pins of the external unit are reliably brought into contact with one another by firmly inserting the connect pins of the external unit into the socket contacts 8. Therefore, the connect pins and the socket contacts 8 are joined firmly, thus causing difficulty in removing the IC memory card 7 from the external unit. When the IC memory card 7 is removed by hand, the hand may slip because the main surface of the panel 4 has no means that can be held by the fingers. Therefore, the IC memory card cannot be easily removed.
The foregoing problem becomes critical with an IC memory card of the type having a connector disposed on the longer side because the major portion of the IC memory card is inserted into the external unit and thus only a small area is available to be held by the hand when the IC memory card has been connected to the external unit. In this case, a large force is required to remove the IC memory card because a multiplicity of connector pins are provided.